feat: init nofxi - AI Trading Agent module

NOFXi — Your AI Trading Agent, built on NOFX.

Architecture:
- Agent Core: intent routing, conversation memory, trade confirmation
- Memory: SQLite (trades, conversations, preferences, strategies)
- Thinking: LLM client (OpenAI/claw402/DeepSeek compatible)
- Execution: Bridge to NOFX trader engine (9 exchanges)
- Perception: Market monitor, price alerts, anomaly detection
- Interaction: Telegram bot + REST API + OpenAI-compatible endpoint

Features:
- Natural language trading (中英文)
- /buy /sell /analyze /watch /alert /positions /balance
- Daily P/L reports, portfolio risk checks
- Trade confirmation flow (safety first)
- Price polling and alert notifications

nofxi/internal/memory/memory.go

@@ -0,0 +1,11 @@
+// Package memory implements the Memory Layer.
+//
+// Provides persistent storage for:
+// - Trade history and P/L tracking
+// - Conversation context (per-user message history)
+// - User preferences and risk profiles
+// - Strategy performance metrics
+// - Market pattern snapshots
+//
+// Backend: SQLite (pure Go driver, zero CGO)
+package memory